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在世界范围内,沉积盆地高超压区的压力预测和安全钻井是长久未能解决的难题。在钻井过程中可能引起各种钻井工程事故的主要原因是渗透砂岩层内的高压,而现在通用的压力预测和监测方法却建立在低渗透的泥质岩内超压产生及对其岩性、物性变化影响的基础上。本文讨论了沉积盆地内异常高压分布的特征,着重探讨了在渗透性砂岩层中异常流体压力产生的机制,划分出自源、邻源和他源3种成因类型,并讨论了各类超压对钻井工程的危害性和可预测性。他源高压是预测性最差而危害性最高的超压类型,以开启断裂或先前钻井造成的原先过剩压力不同地层间的连通而在较浅处形成的高超压为最。分析了平衡深度法为基础的压力预测方法存在的缺陷后,笔者提出一些在高超压盆地内进行压力预测和监测的思路。
Around the world, pressure prediction and safe drilling in the overpressured area of the sedimentary basin have long been a problem that can not be solved. The main reason that may cause various drilling engineering accidents during drilling is the infiltration of high pressure in the sandstone formation. Nowadays, the common pressure prediction and monitoring methods are based on the overpressure generation in the low-permeability mudstone and its lithology, physical property On the basis of changes. In this paper, the characteristics of anomalous high pressure distribution in sedimentary basins are discussed. The mechanism of anomalous fluid pressure in permeable sandstone layers is discussed. Three types of genesis, ie, source, adjacent source and other source, are discussed. Drilling engineering hazards and predictability. He source pressure is the most predictive and the most dangerous type of overpressure, and the overpressure formed at the shallower is the most open at the beginning of the fracture or the previous excess pressure caused by previous drilling. After analyzing the flaws in the pressure prediction method based on the equilibrium depth method, the author puts forward some ideas for pressure prediction and monitoring in the overpressured basin.